Poly N-cyclic aromatic ligands bonded to solid supports for removing and concentrating ions from solutions

ABSTRACT

A method and composition for the concentration and removal of desired metal ions from a source solution by contacting the solution with an N-cyclic aromatic hydrocarbon-containing ligand covalently bonded to a solid support through a hydrophilic spacer of the formula SS--A--X--(L) n  where SS is a solid support, A is covalent linkage mechanism, X is a hydrophilic spacer grouping, L is an N-cyclic aromatic containing ligand group and n is an integer of 1 to 6. X or L combined will not contain more than two amine nitrogen atoms. There will preferably be at least four N-cyclic groups present of which pyridine, pyrimidine, pyraxine, imidazole, quinoline, isoquinoline, naphthyridine, pyridopyridine, phenanthroline are representative. The desired ions in the source solution are bound to the ligands and are subsequently separated by contacting the ligand containing compound with a smaller volume of a receiving solution that removes the bound ions for recovery in concentrated form in the smaller volume of the receiving solution.

This application is a 371 application Ser. No. of PCT/US97/11054, filedJun. 24, 1997 which is based on U.S. Provisional Application Ser. No.60/020,331, filed Jun. 24, 1996.

FIELD OF THE INVENTION

This invention relates to compositions comprising one or more N-cyclicaromatic hydrocarbon ligands the composite of which contains at leasttwo, and preferably four or more N-cyclic groups bonded through anappropriate hydrophilic spacer grouping to a solid support and to theuse of such compositions in the removal or concentration of specificions from solutions. More particularly, this invention relates tocompositions containing one or more N-cyclic aromatic hydrocarboncontaining ligands the composite of which contains at least two, andpreferably four or more N-cyclic groups bonded through a hydrophilicspacer grouping to a solid support in such a manner that the presence ofamine nitrogen atoms are minimized and to the use of such compositionsin the removal of specified metal ions from solutions.

BACKGROUND OF THE INVENTION

Methods for the concentration and removal of selected ions from asolution that will often contain a variety of ions, both cationic andanionic, across a wide pH range, represents a real need in the modernera of advanced technologies. A significant improvement in the art doesexist which provides for the concentration and/or removal of a selectedion from a solution using an organic ligand that is covalently bound,through an organic spacer, to a solid support such as silica gel, glassbeads, alumina, titania, zirconia nickel oxide, polyacrylate, orpolystyrene. The organic ligand provides for coordinative or chelativeion bonding with significant levels of selectivity. The combination oforganic ligand and solid support provides for the incorporation of sucha composition into a column for subsequent use much as pure silica gelis used in column chromatography. By passing a solution containing ions,wherein one ion is desired to be trapped to the exclusion of any otherions, through a column containing a suitable ligand designed to trap thetargeted ion, the targeted ion is selectively and exclusively removedfrom the solution. The trapped ion may be flushed or "un-trapped" bypassing a second solution through the column. The second solution isformulated such that it has a greater affinity for the trapped ions thanthe ion trap ligand does, allowing for the trapped ions to be flushedfrom the column. In this manner the targeted ion is selectively removedfrom any other ions in the solution.

Compositions comprising selective ion binding organic ligands covalentlyattached to solid supports through organic spacers, such as describedabove, are illustrated in numerous patents, of which the following arerepresentative: U.S. Pat. No. 4,952,321 to Bradshaw et al. disclosesamine-containing hydrocarbon ligands; U.S. Pat. Nos. 5,071,819 and5,084,430 to Tarbet et al. disclose sulfur and nitrogen-containinghydrocarbons as ion-binding ligands; U.S. Pat. Nos. 4,959,153 and5,039,419 to Bradshaw et al. disclose sulfur-containing hydrocarbonligands; U.S. Pat. Nos. 4,943,375 and 5,179,213 to Bradshaw et al.disclose ion-binding crowns and cryptands as ligands; U.S. Pat. No.5,182,251 to Bruening et al. discloses aminoalkylphosphonicacid-containing hydrocarbon ligands; U.S. Pat. No. 4,960,882 to Bradshawdiscloses proton-ionizable macrocyclic ligands; U.S. Pat. No. 5,078,978to Tarbet et al. discloses amino-pyridine-containing hydrocarbonligands; U.S. Pat. No. 5,244,856 to Bruening et al. disclosespolytetraalkylammonium and polytrialkylamine-containing hydrocarbonligands; U.S. Pat. No. 5,173,470 to Bruening et al. discloses thioland/or thioether-aralkyl nitrogen-containing hydrocarbon ligands; andU.S. Pat. No. 5,190,661 to Bruening et al. discloses sulfur-containinghydrocarbon ligands also containing electron withdrawing groups. Theseligands are generally attached to the solid support via a suitablehydrocarbon spacer.

One problem with some of these compositions is that they are not asefficient as sometimes desired when using acid solutions because of theeffect of acid on the ability of these compositions to complextransition and other metal ions as well as allowing for a greatervariety of selectivity among the transition metal ions themselves.

The present invention ameliorates this problem.

OBJECTS AND SUMMARY OF THE INVENTION

It is an object of this invention to provide a composition and methodfor the removal of transition metal ions from a solution utilizingcompositions comprising one or more N-cyclic hydrocarbon ligands thecomposite of which contains at least two, and preferably four or moreN-cyclic groups bonded to a solid support via an appropriate hydrophilichydrocarbon spacer.

The unique properties of the N-cyclic hydrocarbons having aromaticproperties such as pyridine, pyrimidine, pyrazine, imidazole, quinoline,isoquinoline, naphthyridine, pyridopyridine, phenanthroline or similarN-cyclic hydrocarbon containing ligands and combinations thereof withnot more than two amine nitrogen atoms included covalently bonded toappropriate inorganic and organic solid supports form the basis of thepresent invention. The invention also encompasses processes for usingthe compositions for the separation of desired ions or groups of ionsparticularly under mildly acidic to acidic conditions.

The compounds of the present invention comprise suitable N-cyclicaromatic ligands such as those noted above which are covalently bondedthrough a hydrophilic spacer grouping to a silicon, carbon, nitrogen,oxygen or sulfur atom and further covalently bonded to an inorganic orpolymeric organic solid support and are represented by the followingFormula 1:

    SS--A--X--(L).sub.n                                        (Formula 1)

where SS is a solid support, A is a covalent linkage mechanism, X is ahydrophilic spacer grouping, L is an N-cyclic aromatic containing ligandgroup and n is an integer of 1 to 6 with the proviso that when n is 1, Lmust contain at least two and preferably four or more N-cyclic aromaticrings, and with the further proviso that when X or L contains aminenitrogen atoms there will be not more than two such atoms present andthey will preferably be tertiary amine nitrogen atoms. Nitrogen atomsforming part of an amide, thioamide, and the like are not consideredamine nitrogens. Preferably (L)_(n) will be such that at least fourN-cyclic groups will be present. Most preferably, from four to sixN-cyclic groups will be present with four N-cyclic group being optimal.It is not as important whether n is a numeral of 1 to 6 as it is thatthe ligand(s) present preferably have a composite of four to sixN-cyclic groups. Thus, for a composition containing four N-cyclicgroups, aside from functionality, it does not matter whether there arefour pyridine groups, two phenanthroline groups, two pyridyl-imidazolegroups, or a terpyridyl and a quinolyl group present in the ligand(s).For purposes of definition, an N-cyclic ring containing compound havingtwo nitrogens in separate rings, such as phenanthroline, is consideredas containing two N-cyclic rings. Hence, two phenanthroline structurescontain four N-cyclic rings.

Representative of the inorganic solid support matrices are membersselected from the group consisting of sand, silica gel, glass, glassfibers, alumina, zirconia, titania, and nickel oxide and otherhydrophilic inorganic supports of a similar nature as well as mixturesof such inorganic materials. Representative of the polymeric organicsolid support matrices are members selected from the group consisting ofpolyacrylate, polystyrene, polyphenol, and other hydrophilic organicsupports as well as mixtures of such polymeric materials.

Exemplary of covalent linkages represented by A are members selectedfrom the group consisting of Si(Y,Z)--O, O, S, C═N, CO, CONH, CSNH, COO,CSO, NH, NR, SO, SO₂, SO₂ NH, C₆ H⁴, CH₂ C₆ H₄, and the like. Y and Zcan independently represent members selected from the group consistingof Cl, Br, I, alkyl, alkoxy, substituted alkyl or substituted alkoxy andO--SS (when SS is an inorganic solid support). When Y and Z moieties areother than O--SS they are functionally classified as leaving groups,i.e. groups attached to the silicon atom which, when reacted with anO--SS material, may leave or be replaced by the O--SS. If any suchfunctional leaving groups are left over after reacting a siliconcontaining spacer group or spacer/ligand group with the inorganic solidsupport material, these groups will have not affect the interactionbetween the desired ion and the N-cyclic ligand-attached via a spacer tothe solid support. R can be hydrogen, alkyl or aryl. Alkyl or alkoxymeans a 1-6 carbon member alkyl or alkoxy group which may be substitutedor unsubstituted, straight or branched chain. By substituted is meant bygroups such as Cl, Br, I, NO₂ and the like.

X is a spacer grouping which is of a functional nature that it issufficiently hydrophilic to function in an aqueous environment and willseparate the ligand from the solid matrix support surface to maximizethe interaction between the ligand and desired ion being separated. Xmay be made up of various combinations of alkyl, aryl, alkaryl andaralkyl moieties which may also contain one or more O, S, tert-aminenitrogen, amide, alkylamide, sulfonyl, sulfonamide and carbonylfunctionalities. The alkyl, aryl and aralkyl moieties may also besubstituted by --OH, --SH, --Cl, and the like. Preferably X will containfrom about 4 to 20 carbon atoms.

Such spacers may be represented by the following Formula 2: ##STR1##

In the Formula 2, the following definitions apply to both upper andlower case letters. Q can be alkylene, arylene, aralkylene oralkarylene. J can be O, S, or NR. T can be SO₂ N<, alkylene, N<, or,when k is 0, T can be O, S or NR. B and G can be O, S, N, CON<, CH₂CON<, NHCOCH₂ -- or SO₂ N<. D and M can be N< or CONH--. In the lowercase, n can be an integer of 1 to about 10, and is preferably 1 to 3.The letters m, o, p, e, f, h, j and k are independently 0 or 1 and a andg are 0 to 3. Preferably p is 1.

Representative specific spacer options are shown in Table 1

                                      TABLE 1                                     __________________________________________________________________________    Representative Spacer (X) Options.                                            X No.                                                                             1   2   3  4     5   6  7  8   9                                          __________________________________________________________________________    n   3   2   3  3     2   3  1  3   3                                          J           O                  O                                              m                 0                1                                                                                  0                                     Q         phenyll                                                                         CH.sub.2                                                                               phenyl                                                                             O        CH.sub.2                                   o                 0                1                                                                                  0                                     T       SO.sub.2 N<                                                                       CH   N<      SO.sub.2 N<                                                                   N< N< CH  N<                                         p                 1     1                                                                                1                                                                                     1                                                                                 1                                      a           0     2            0                                              B           O    NHCOCH.sub.2                                                                                O                                              c           2                  1                                              D           N<                 CONH                                           e           1     0            1                                              f                 1                1                                                                                  0                                     g           1     2            1                                              G           O     NHCOCH.sub.2                                                                               O                                              h           2                                                    1            j           1     0            1                                              k                 1                1                                                                                  0                                     M           N<                 CONH                                           __________________________________________________________________________

When the solid support SS is an organic resin or polymer, such asphenolic resins, polystyrenes and polyacrylates, it will generally be ahydrophilic polymer or polymer derivatized to have a hydrophilic surfaceand contain polar functional groups. The ligand L will then generallycontain a functional grouping reactive with an activated polar group onthe polymer. The covalent linkage A and spacer X will then be formed bythe covalent bonding formed by the reaction between the activated polargroup from the polymer and the functional group from the ligand and maybe represented by Formula 3:

    --(CH.sub.2).sub.x --(Y).sub.y --(CH.sub.2).sub.z --       (Formula 3)

where y is an integer or 0 or 1, x and z are independently integersbetween 0 and 10 and Y is a functional group or aromatic linkage such asan ether, sulfide, imine, carbonyl, ester, thioester, amide, thioamide,amine, alkylamine, sulfoxide, sulfone, sulfonamide, phenyl, benzyl, andthe like. Preferably y is 1.

As noted above the ligand(s) L can be represented by a series ofN-cyclic hydrocarbons having aromatic properties such as pyridine,pyrimidine, pyrazine, imidazole, quinoline, isoquinoline, naphthyridine,pyridopyridine, phenanthroline or similar N-cyclic hydrocarboncontaining ligands. Representative of such ligand moieties are pyridyl,picolyl, 4,5-phenanthroline, dipyridyl, bispyridyl, terpyridyl,pyridyl-imidazol, pyrimidinyl, pyrazinyl, quinoyl, and the like. TheseN-cyclics can exist in various isomeric configurations and the covalentpoint of attachment to the spacer grouping can vary, e.g. 2, 3 or4-pyridyl, etc. Preferred N-cyclic hydrocarbons having aromaticproperties are those containing pyridine, imidazole and phenanthrolinering structures. Representative of compounds having pyridine rings thatare considered within the definition of pyridine are picoline and theisomeric forms of bipyridyl and terpyridyl.

It is to be noted that the solid supports SS, the covalent linkages Aand the spacers X have been used in the prior art to attach ligands tosolid supports. Hence, the novelty of the present invention lies infinding that the attachment of poly N-cyclic moieties to solid supportsby proper linkages provides a composition having two and preferably atleast four N-cyclics in the ligand(s) which function exceptionally wellin the removal of desired ions from solutions.

Representative SS--A--X--(L)_(n) compositions I-IX follow. Thesegenerally correspond to the X spacer groupings 1-9, in Table 1. However,in certain instances, portions of the spacer X, listed in Table 1, whichbond to the ligand are structurally shown in compositions I-IX whereasthe portions that attach to the silane support A are not. One thereforeneeds to consider both Table 1 and the structures of compositions I-IXto recognize the entire spacer X as listed in Table 1. For that reason,the portions of X not specifically drawn into compositions I-IX areidentified as X'. However, one skilled in the art can readily ascertainfrom the structures of compositions I-IX and Table 1 what is consideredto be the ligand or ligands (L)_(n) and the spacer X. Therefore, forillustrative purposes, in each formula of compositions I-IX the SS is aninorganic material such as silica, the covalent attachment A is atrimethoxysilyl group, and the spacer portion X' is the portion of aspacer in Table 1 that is not specifically identified in the structuralformula. Any other solid supports or covalent linkages could be used andwould be apparent to one skilled in the art.

Composition I containing a 2,2':6",2"-terpyridyl ligand ##STR2##Composition II containing two 2-picolyl ligands ##STR3## Composition IIIcontaining four 2-pyridyl ligands ##STR4## Composition IV containing two2(2'-pyridyl)imidazoyl ligands ##STR5## Composition V containing two2-pyridyl ligands ##STR6## Composition VI containing two 2-pyridylligands ##STR7## Composition VII containing one 8-quinoyl and one2-picolyl ligand ##STR8## Composition VIII containing two1,10-phenanthroline ligands ##STR9## Composition IX containing two4'methyl 2,2' dipyridyl ligands ##STR10##

The use of N-cyclic aromatic ligand containing compositions illustratedabove having not more than two amine nitrogens both greatly reduces theeffect of acid on the ability to complex transition and other metal ionsas well as allowing for a greater variety of selectivity among thetransition metal ions themselves.

The N-cyclic aromatic ligand containing compositions as broadly shown inFormula 1, and particularly those having four or more N-cyclic groups,are characterized by high selectivity for and removal of desired ions orgroups of desired ions such as Mn²⁺, Co²⁺, Fe²⁺, Fe³⁺, Ni²⁺, Cu²⁺, Zn²⁺,Cd²⁺, Hg²⁺, Pd²⁺, Au³⁺, Ag⁺, and Pb²⁺ present at minority concentrationsfrom the source phase solution containing a mixture of these metal ionswith the ions one does not desire to remove (i.e. referred to as"undesired ions") which may be present in much greater concentrations inthe solution even under moderately acidic conditions. The separation isaccomplished, even in the presence of other complexing agents or matrixconstituents, particularly acids, in a separation device, such as acolumn, through which the solution is flowed. The process of selectivelyremoving and concentrating the desired ion(s) is characterized by theability to quantitatively complex from a larger volume of solution thedesired ion(s) when they are present at minority concentrations. Thedesired ions are recovered from the separation column by flowing throughit a small volume of a receiving phase which contains a solubilizingreagent which need not be selective, but which will strip the desiredions from the N-cyclic ligand quantitatively. The recovery of thedesired metal ions from the receiving phase is readily accomplished byknown procedures.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

As summarized above, the present invention is drawn to novel polyN-cyclic aromatic hydrocarbon ligands the composite of which contains atleast two, and preferably four or more N-cyclic groups containing notmore than two amine groups near the active binding site covalently boundthrough a hydrophilic spacer to a solid matrix or support, to form thecompounds of Formula 1. The compositions must have at least two andpreferably contain four or more N-cyclic groups. The invention is alsodrawn to the concentration and removal of certain desired ions such asMn²⁺, Co²⁺, Fe²⁺, Fe⁺, Ni²⁺, Cu²⁺, Zn²⁺, Cd²⁺, Hg²⁺, Pd²⁺, Au³⁺, Ag⁺,and Pb²⁺ from other ions and also from each other, particularly inmoderately acidic solutions.

For example, effective and efficient methods of recovery and/orseparation of metal ions from other metal ions, such as (1) separationand concentration of Co²⁺, Ni²⁺, or Cu²⁺ ions from solutions containingFe²⁺, Mn²⁺, and Zn²⁺ ions and which may also contain Ca²⁺, Mg²⁺, Na⁺, K⁺ions even when such solutions are moderately acidic; (2) separation ofsmall combined amounts of Mn²⁺, Co²⁺, Ni²⁺, Cu²⁺, and Zn²⁺ ions fromsolutions containing large amounts of Na⁺, K⁺, Ca²⁺, Mg²⁺, and acid and(3) separation of Pb²⁺, Cd²⁺, and/or Hg²⁺ as toxic wastes from acidicsolutions represent a real need for which there are no feasible andestablished procedures or for which more economical processes aredesired. Such solutions from which such ions are to be concentratedand/or recovered are referred to herein as "source solutions." In manyinstances the concentration of desired ions in the source solutions willbe much less than the concentration of other or undesired ions fromwhich they are to be separated.

The concentration of desired ions is accomplished by forming a complexof the desired ions with a poly N-cyclic ligand compound shown inFormula 1 by flowing a source solution containing the desired ionsthrough a column packed with poly N-cyclic containing Formula 1 compoundto attract and bind the desired ions to the N-cyclic ligand portion ofsuch compound and subsequently breaking the ligand compound-complex byflowing a receiving liquid in much smaller volume than the volume ofsource solution passed through the column to remove and concentrate thedesired ions in the receiving liquid solution. The receiving liquid orrecovery solution forms a stronger complex with the desired ions thandoes the ligand portion of a Formula 1 compound and thus the desiredions are quantitatively stripped from the ligand in concentrated form inthe receiving solution. The recovery of desired ions from the receivingliquid is accomplished by known methods.

The process of selectively and quantitatively concentrating and removinga desired ion or group of desired ions present at low or minorityconcentrations from a plurality of other undesired ions in a multipleion source solution in which the undesired ions, along with acid(s) andother chelating agents may be present at much higher concentrations,comprises bringing the multiple ion containing source solution intocontact with a N-cyclic aromatic hydrocarbon ligand containingcomposition as shown in Formula 1 which causes the desired ion(s) tocomplex with the N-cyclic ligand(s) portion of the compound andsubsequently breaking or stripping the desired ion from the complex witha receiving solution which forms a stronger complex with the desiredions than does the ligand or which forms a stronger complex with theligand. The receiving or recovery solution contains only the desiredions in a concentrated form.

The N-cyclic aromatic ligand containing solid support compositionfunctions to attract the desired ions (DI) according to Formula 4:

    SS--A--X--(L).sub.n +DI→SS--A--X--(L).sub.n :DI     (Formula 4)

Except for DI, Formula 4 is the same as Formula 1 wherein L stands forthe N-cyclic aromatic hydrocarbon containing ligand. DI stands fordesired ion being removed.

Once the desired ions are bound to the poly N-cyclic aromatichydrocarbon-containing ligand, they are subsequently separated by use ofa smaller volume of a receiving liquid according to Formula 5:

    SS--A--X--(L).sub.n :DI+RL→SS--A--X--(L).sub.n and RL+DI(Formula 5)

where RL stands for the receiving liquid.

The preferred embodiment disclosed herein involves carrying out theprocess by bringing a large volume of the source multiple ion solution,which may contain hydrogen ions and may also contain other chelatingagents, into contact with a N-cyclic aromatic hydrocarbon-containingligand-solid support compound of Formula 1 in a separation columnthrough which the mixture is first flowed to complex the desired metalions (DI) with the ligand-solid support compound as indicated by Formula4 above, followed by the flow through the column of a smaller volume ofa receiving liquid (RL), such as aqueous solutions of thiourea, Na₂ S₂O₃, HI, HBr, HCl, H₂ SO₄, HNO₃ NaI, ethylenediamine, Na₄ EDTA, glycine,and others which form a stronger complex with the desired ion than doesthe poly N-cyclic aromatic hydrocarbon-containing ligand bound to thesolid support or forms a stronger complex with the N-cyclic aromatichydrocarbon-containing ligand bound to solid support than does thedesired ion. In this manner the desired ions are carried out of thecolumn in a concentrated form in the receiving solution as indicated byFormula 5. The degree or amount of concentration will obviously dependupon the concentration of desired ions in the source solution and thevolume of source solution to be treated. The specific receiving liquidbeing utilized will also be a factor. The receiving liquid does not haveto be specific to the removal of the desired ions because no other ionswill be complexed to the ligand. Generally speaking the concentration ofdesired ions in the receiving liquid will be from 20 to 1,000,000 timesgreater than in the source solution. Other equivalent apparatus may beused instead of a column, e.g., a slurry which is filtered which is thenwashed with a receiving liquid to break the complex and recover thedesired ion(s). The concentrated desired ions are then recovered fromthe receiving phase by known procedures.

Representative of desired ions which have strong affinities for polyN-cyclic aromatic hydrocarbon-containing ligands bound to solid supportsare Mn²⁺ Co²⁺, Fe²⁺, Fe³⁺, Ni²⁺, Cu²⁺, Zn²⁺, Cd²⁺, Hg²⁺, Pd²⁺, Au³⁺,Ag⁺, and Pb²⁺. This listing of exemplary ions is not comprehensive andis intended only to show the types of preferred ions which may be boundto the ligands attached to solid supports in the manner described above.The affinity of the ligand to the ions will obviously vary dependingupon the ion and the ligand configuration. Hence it is possible that,even in the above listing, those ions having the stronger affinity forthe ligand will be selectively removed from other ions in the listingwhich have a weaker affinity for the particular ligand. Hence, by properchoice of ligands and makeup of the source solution it is also possibleto separate and concentrate one desired ion from another. Therefore, theterminology "desired ions" and "undesired ions" is relative and the ionhaving the stronger affinity to the ligand will generally be the"desired" ion. What is or is not a desired ion can readily be determinedby one skilled in the art from the information contained herein and doesnot require extensive or undue experimentation.

The process of the invention is particularly adaptable to the removal ofCo²⁺, Ni²⁺, or Cu²⁺ ions from source solutions which may additionallycontain Ca²⁺, Mg²⁺, Na³⁰ , K⁺, H⁺, SO₄ ²⁻, Cl⁻, HSO₄ ⁻, Br⁻, NO₃ ⁻,Zn²⁺, Mn²⁺, Fe³⁺ and Fe²⁺. In these instances, the receiving liquid forremoving the ion(s) bound to the ligand will preferably be stronglyconcentrated H₂ SO₄.

The following examples are representative of the preparation of polyN-cyclic ligands bound through a spacer grouping and an alkoxy silanecovalent linkage to a solid support.

EXAMPLE 1

A 0.5 gram amount (2 mmol) of 4-methyl,4'chloromethyl-2,2'-bipyridineligand in 20 mls of acetonitrile was mixed with 1.4 grams of sodiumcarbonate and 0.2 g. (0.91 mmol) of 3-aminopropyltriethoxysilane as aspacer. After 5 hours at 70° C. the acetonitrile solvent was evaporatedand 100 mls of toluene was added. The mixture was filtered and 0.4 gramsof silica gel (Amicon, grade 646) was added to the solution and heatedovernight at 90° C. to allow the attachment of the ligand spacer to thesilica gel support. The silica gel/ligand product was filtered andwashed with toluene, methanol and then water and methanol. The productwas dried in a vacuum oven at 60° C. The resulting product was thatshown as Composition IX wherein the spacer X' is propyl, A is a silaneand SS silica gel.

EXAMPLE 2

A 4.62 (0.02 mole) gram sample of ethyl (2-pyrid-2¹ -yl) Imidazolacetatewas refluxed with 1.03 grams (0.01 mole) of diethylenetriamine in 50 mlsof ethanol for 8 days. The reaction proceeded according to the followingreaction scheme: ##STR11##

The ethanol solvent was evaporated and the residue chromatographed on acolumn with silica gel using methanol. The product yield was about 37%.

EXAMPLE 3

To 0.473 grams (1 mmol) of the product of Example 2 was added 0.27 grams(0.1 mmol) of 3-bromopropyltriinethoxysilane and 0.1 gram (1.1 mmol) ofsodium bicarbonate in 50 mls of DMF (dimethylformamide). The mixture washeated at 75° C. for 18 hours. Then 0.5 grams of silica gel (Amicon,grade 646) was added and the reaction was continued for 8 hours more toallow the attachment of the ligand spacer to the silica gel support. Thesilica gel/ligand product was filtered and washed with DMF and thenwater and methanol. The product was dried in a vacuum oven at 65° C. Theresulting product was that shown as Composition IV wherein the spacer X'is propyl, A is a silane and SS is silica gel.

EXAMPLE 4

To 0.473 grams (1 mmol) of the product of Example 2 was added 0.48 grams(50% solution, 0.73 mmol) of2-(4-chlorosulfonyl-phenyl)-ethyltrimethoxysilane and 0.26 gram (2.5mmol) of triethylamine in 15 mls of DMF. The mixture was heated at 80°C. for 5 hours. Then 0.7 grams of silica gel (Amicon, grade 646) wasadded and the reaction was continued for 24 hours more to allow theattachment of the ligand spacer to the silica gel support. The silicagel/ligand product was filtered and washed with DMF and then water andmethanol. The product was dried in a vacuum oven at 65° C. The resultingproduct was that shown as Composition IV wherein the spacer X' issulfonylphenylethyl (spacer 2 in Table 1 attached to nitrogen), A is asilane and SS is silica gel.

EXAMPLE 5

To 0.7 grams (1.5 mmol) of the product of Example 2 was added 0.4 grams(1.65 mmol) of 3-glycidoxypropyltrimethoxysilane in 30 mls of ethanoland refluxed for 18 hours. The mixture was transferred to a highpressure bottle and heated at 130° C. for 16 hours. Then 0.7 grams ofsilica gel (Amicon, grade 646) was added and heated an additional 24hours to allow the attachment of the ligand spacer to the silica gelsupport. The silica gel/ligand product was filtered and washed with DMFand then water and methanol. The product was dried in a vacuum oven at65° C. The resulting product was that shown as Composition IV whereinthe spacer X' is --CH₂ CH(OH)CH₂ O(CH₂)₃ --, A is a silane and SS issilica gel.

Other combinations of N-cyclic ligands attached via spacers X, covalentlinkages, A and solid supports SS can be readily ascertained by thoseskilled in the art based on the description contained herein. No claimis made as to the novelty of ligands L per se as it is known thatN-cyclic compounds have an affinity for certain ions. However, thecombining of two, three, or preferably four or more, N-cyclics to asolid support in the manner described herein is believed to be novel.

The following examples are illustrative of the manner in which the polyN-cyclic ligands bound to a solid support may be used in the removal ofdesired ions.

EXAMPLE 6

A 0.5 gram sample of the bisbipyridine ligand attached to silica gel ofExample 1 was placed in a column. A 20 ml source solution of 0.001 MCo.²⁺ in 0.03 M Fe³⁺ and 0.1 M H₂ SO₄ was drawn through the column. A 5ml aqueous solution of 1 M H₂ SO₄ was then passed through the column towash out the loading solution remaining in the column. The Co ion andany co-retained ferric ion was then eluted with 5 ml of 80° C. 1500 ppmCu, 0.5 M Na₂ SO₃, 4 M H₂ SO₄. Analysis of the above solutions by FlameAtomic Absorption Spectroscopy (AA) showed that greater than 95% of theCo originally in the 20 ml solution described above was in the 5 mlreceiving solution. Furthermore, the Fe level in the receiving solutionwas only 210 mg/l.

EXAMPLE 7

A 0.1 gram sample of the di(pyridyl-imidazole) ligand attached to silicagel of Example 4 was placed in a column. A source solution of 74 mg/lNi²⁺ in 0.01 M H₂ SO₄ and 0.01 M Fe³⁺ was drawn through the column untilthe column was in full equilibrium with the solution. A 50 ml aqueoussolution of 0.01 M H₂ SO₄ was then passed through the column to wash outthe loading solution remaining in the column. The Ni ion was then elutedwith 5 ml of 1 M H₂ SO₄. Analysis of the above solutions by AA showedthat the 5 ml receiving solution containing 147 mg/l Ni. Furthermore,the Fe level in the receiving solution was <10 mg/l.

EXAMPLE 8

A 0.1 gram sample of the di(pyridyl-imidazole) ligand attached to silicagel of Example 3 was placed in a column. A 1 ml source solution of 450mg/l Ni²⁺, 680 mg/l Fe³⁺, 42,000 mg/l Cd²⁺, 2,400 mg/l Co³⁺, and 90,000mg/l Zn²⁺ was drawn through the column. A 4 ml aqueous solution of 0.01M H₂ SO₄ was then passed through the column to wash out the loadingsolution remaining in the column. The Ni ion was then eluted with 1 mlof 1 M H₂ SO₄. Analysis of the above solutions by AA showed that greaterthan 99% of the Ni originally in the 1 ml solution described above wasin the 1 ml receiving solution. Furthermore, the Fe, Ni, Cd and Znlevels in the receiving solution were all >5 mg/l and the Co level was50 mg/l.

What is claimed is:
 1. A composition comprising a N-cyclic aromatichydrocarbon-containing ligand covalently bonded to a solid supportthrough a hydrophilic spacer having the formula:

    SS--A--X--(L).sub.n

where SS is a solid support, A is a covalent linkage mechanism, X is ahydrophilic spacer grouping, L is an N-cyclic aromatic containing ligandgroup and n is an integer of 1 to 6 with the proviso that (L)_(n)contains a composite of at least four N-cyclic groups, and with thefurther proviso that when X or L contains amine nitrogen atoms therewill be not more than two such atoms present.
 2. A composition accordingto claim 1 wherein (L)_(n) contains from four to six N-cyclic groups. 3.A composition according to claim 2 wherein the N-cyclic aromatichydrocarbon is a member selected from the group consisting of pyridine,pyrimidine, pyrazine, imidazole, quinoline, isoquinoline, naphthyridine,pyridopyridine, phenanthroline and combinations thereof.
 4. Acomposition according to claim 3 wherein the N-cyclic aromatichydrocarbon is a member selected from the group consisting of pyridine,isoquinoline and phenanthroline and combinations thereof.
 5. Acomposition according to claim 4 wherein the N-cyclic aromatichydrocarbon is pyridine.
 6. A composition according to claim 4 whereinthe N-cyclic aromatic hydrocarbon is a pyridyl imidazole combination. 7.A composition according to claim 3 wherein SS is an inorganic solidsupport selected from the group consisting of sand, silica gel, glass,glass fibers, alumina, zirconia, titania, and nickel oxide andcombinations thereof.
 8. A composition according to claim 7 wherein A isa member selected from the group consisting of Si(Y,Z)--O, wherein Y andZ can independently represent members selected from the group consistingof Cl, Br, I, alkyl, alkoxy, substituted alkyl or substituted alkoxy andO--SS.
 9. A composition according to claim 8 wherein X is a memberrepresented by the formula: ##STR12## wherein Q is a member selectedfrom the group consisting of alkylene, arylene, aralkylene oralkarylene; J is a member selected from the group consisting of O, S, orNR; T is a member selected from the group consisting of SO₂ N<,alkylene, N<, O, S or NR; B and G are independently members selectedfrom the group consisting of O, S, N, CON<, CH₂ CON<, NHCOCH₂ -- or SO₂N<; D and M are independently members selected from the group consistingof N< or CONH--; n is an integer of 1 to 10; m, o, p, e, f, h, j and kare independently 0 or 1; and a and g are independently 0 to
 3. 10. Acomposition according to claim 3 wherein SS is a polymeric organic solidsupport matrices selected from the group consisting of polyacrylate,polystyrene, and polyphenol and combinations thereof.
 11. A compositionaccording to claim 10 wherein A and X combined are represented by theformula:

    --(CH.sub.2).sub.x --(Y).sub.y --(CH.sub.2).sub.z --

where y is an integer or 0 or 1; x and z are independently integersbetween 0 and 10; and Y is member selected from the group consisting ofO, S, C═N, CO, CONH, CSNH, COO, CSO, NH, NR, SO, SO₂, SO₂ NH, C₆ H⁴ andCH₂ C₆ H₄ where R is alkyl.
 12. A method for the concentration andremoval of desired metal ions from a source solution which comprises(a)bringing said source solution having a first volume into contact with acompound comprising a N-cyclic aromatic hydrocarbon-containing ligandcovalently bonded to a solid support through a hydrophilic spacer havingthe formula:

    SS--A--X--(L).sub.n

where SS is a solid support, A is a covalent linkage mechanism, X is ahydrophilic spacer grouping, L is an N-cyclic aromatic containing ligandgroup and n is an integer of 1 to 6 with the proviso that (L)_(n)contains a composite of at least four N-cyclic groups, and with thefurther proviso that when X or L contains amine nitrogen atoms therewill be not more than two such atoms present; (b) removing said sourcesolution from contact with said compound to which said desired metalions have been complexed; and (c) contacting said compound having saiddesired metal ions complexed thereto with a smaller volume of areceiving solution having a greater affinity for said desired metal ionsthan said compound thereby breaking said complex and recovering thedesired metal ions in concentrated form in said smaller volume of saidreceiving solution.
 13. A method according to claim 12 wherein (L)_(n)contains from four to six N-cyclic groups.
 14. A method according toclaim 13 wherein the N-cyclic aromatic hydrocarbon is a member selectedfrom the group consisting of pyridine, pyrimidine, pyrazine, imidazole,quinoline, isoquinoline, naphthyridine, pyridopyridine, phenanthrolineand combinations thereof.
 15. A method according to claim 14 whereinsaid desired ions are members selected from the group consisting ofMn²⁺, Co²⁺, Fe²⁺, Fe³⁺, Ni²⁺, Cu²⁺, Zn²⁺, Cd²⁺, Hg²⁺, Pd²⁺, Au³⁺, Ag⁺,and Pb²⁺ and combinations thereof.
 16. A method according to claim 15wherein said desired ions are members selected from the group consistingof Co²⁺, Ni²⁺, or Cu²⁺ ions which are to be separated from solutionscontaining Fe²⁺, Mn²⁺, and Zn²⁺ ions.
 17. A method according to claim 15wherein said desired ions are members selected from the group consistingof Mn²⁺, Co²⁺, Ni²⁺, Cu²⁺, and Zn²⁺ ions which are to be separated fromsolutions containing Na⁺, K⁺, Ca²⁺, Mg²⁺ ions.
 18. A method according toclaim 15 wherein said desired ions are members selected from the groupconsisting of Pb²⁺, Cd²⁺, and Hg²⁺ ions which are to be separated fromtoxic waste solutions.
 19. A method according to claim 15 wherein theN-cyclic aromatic hydrocarbon is a member selected from the groupconsisting of pyridine, isoquinoline and phenanthroline and combinationsthereof.
 20. A method according to claim 19 wherein the N-cyclicaromatic hydrocarbon is pyridine.
 21. A method according to claim 19wherein the N-cyclic aromatic hydrocarbon is a pyridyl imidazolecombination.
 22. A method according to claim 15 wherein SS is aninorganic solid support selected from the group consisting of sand,silica gel, glass, glass fibers, alumina, zirconia, titania, and nickeloxide and combinations thereof.
 23. A method according to claim 22wherein A is a member selected from the group consisting of Si(Y,Z)--O,wherein Y and Z can independently represent members selected from thegroup consisting of Cl, Br, I, alkyl, alkoxy, substituted alkyl orsubstituted alkoxy and O--SS.
 24. A method according to claim 23 whereinX is a member represented by the formula: ##STR13## wherein Q is amember selected from the group consisting of alkylene, arylene,aralkylene or alkarylene; J is a member selected from the groupconsisting of O, S, or NR; T is a member selected from the groupconsisting of SO₂ N<, alkylene, N<, O, S or NR; B and G areindependently members selected from the group consisting of O, S, N,CON<, CH₂ CON<, NHCOCH₂ -- or SO₂ N<; D and M are independently membersselected from the group consisting of N< or CONH--; n is an integer of 1to 10; m, o, p, e, f, h, j and k are independently 0 or 1; and a and gare independently 0 to
 3. 25. A method according to claim 15 wherein SSis a polymeric organic solid support matrices selected from the groupconsisting of polyacrylate, polystyrene, and polyphenol and combinationsthereof.
 26. A method according to claim 25 wherein A and X combined arerepresented by the formula:

    --(CH.sub.2).sub.x --(Y).sub.y --(CH.sub.2).sub.z --

where y is an integer or 0 or 1; x and z are independently integersbetween 0 and 10; and Y is member selected from the group consisting ofO, S, C═N, CO, CONH, CSNH, COO, CSO, NH, NR, SO, SO₂, SO₂ NH, C₆ H⁴ andCH₂ C₆ H₄ where R is alkyl.